Performance and mechanism of biosorption of nickel(II) from aqueous solution by non-living Streptomyces roseorubens SY

The biosorption of nickel(II) ions from aqueous solution by non-living strain Streptomyces roseorubens SY was thoroughly investigated as a function of pH, nickel(II) concentration, dosage, temperature, agitation speed and contact time. This versatile strain Streptomyces roseorubens SY was proved to be a highly efficient biosorbent for the removal of nickel(II) from aqueous solution. The optimum adsorption condition was occurred at a pH of 5.0, an initial nickel (II) concentration of 100 mg/L, a biomass of 1.0 g/L, an agitation speed of 150 rpm with a contact time of 60 min. The adsorption behavior of nickel(II) on strain Streptomyces roseorubens SY was evaluated by both Langmuir and Freundlich isotherms, resulting in R-2 of 0.9584 and 0.9166, respectively. The biosorption data showed an excellent fit to Langmuir isotherm and the maximum adsorption capacity of nickel(II) by strain Streptomyces roseorubens SY was found to be 208.39 mg/g at 313 K. The pseudo-second-order model (R-2 = 0.9998) provides the best fit for biosorption data than did pseudo-first-order model (R-2 = 0.8988). Results from thermodynamic analysis indicated that the nickel(II) biosorption by strain Streptomyces roseorubens SY was endothermic and spontaneous. The biosorption mechanism was mainly ascribed to the contributions from functional groups of -OH, C=O, C-O, N-H, etc. Our findings suggest that strain Streptomyces roseorubens SY is a promising, cost-effective and environment-friendly biosorbent for the treatment of industrial wastewater containing nickel(II) ions.